1. Field of the Invention
The present invention relates to a three dimensional computer input device having six degrees of freedom and exhibiting force feedback in response to user-initiated motion of the input device.
2. Description of the Related Art
The ability to depict a cursor in three dimensional space on a computer screen necessitates the ability to move the cursor throughout the three-dimensional space using a user controlled computer input device. Another useful characteristic for a computer input device is to provide tactile feedback to the user in response to user-initiated motion.
The computer mouse is the most widely used device for selectively moving a cursor on a computer display screen. Other common input devices are the track ball and touch screen. However, all of these input devices are restricted to 2 dimensional motion.
In U.S. Pat. No. 5,591,924, the disclosed space ball has the ability to detect three dimensionally applied forces and torques. This device does not, however, provide tactile feedback to the user.
Joysticks are also commonly used as input devices. U.S. Pat. No. 5,589,828 discloses a joystick that is movable at its base in three dimensions and provides feedback in the form of springs. Detectors at the base detect the three dimensional motion of the base. A ball that is graspable by the user is movably connected to the top of the joystick such that it rotates about all three coordinate axes. The ball includes detectors for detecting rotation of the ball. This device thus detects six degrees of motion. It is, however, complex to build, at least in part because for each degree of freedom, two one-dimensional detectors are used--one for positive motion and one for negative motion. Twelve separate detectors, six at the base of the joystick and six at the ball of the joystick, are therefore required to realize the full functionality of this prior art device.